1. Field of the Invention
The present invention relates generally to an apparatus for supporting keys or key blanks during the cutting of bit surfaces into the blade thereof. More particularly, the invention relates to an apparatus for supporting during such cutting keys or key blanks which include a blade having a lower portion which extends away from an upper portion at a predetermined relative angular orientation.
2. Description of Background Art
The prior art includes well known devices for cutting bit surfaces into the blade portion of a key blank. The bit surfaces are cut into the blade at positions which correspond to the positions of complimentary tumbler pins located in a lock, for example, a cylinder lock with a rotatable plug disposed in an outer shell. In such a cylinder lock, the tumbler pins, which extend through openings in the plug, must be raised (and rotated in a Medeco.RTM. brand high security cylinder lock with twisting pins) by the key to a shear line so as allow rotation of the plug within the shell. The level to which each tumbler pin must be moved by the key determines the depth of the corresponding bit surfaces cut in the key blade. Upon insertion of the key blade into the keyway of the lock, the bit surfaces engage and raise each tumbler pin to its proper position, thus allowing one to rotate the plug and operate the lock. The operation of such locks is well known in the art.
One type of apparatus for cutting a key blade utilizes a punch and die block to remove portions of the key blade to form the bit surfaces. Such apparatus typically comprise a base plate (lower jaw) and an upper plate (upper jaw) which clamp the key or a portion thereof to support same while the blade is being cut. The punch is moved downward toward the die block and punches out a portion of the key blade to form the desired bit surface(s). The die block is movable relative the key blade to form each bit of the series of bits which are disposed one after another along the length of the key blade. FIGS. 1 and 2 show a conventional key punch machine having a structure corresponding to that discussed above.
Prior art apparatus such as that shown in FIGS. 1, 2A, 2B and 3 support the key blank by engaging the tip stop and heel of the key blade to fix the position of the key blank in two directions. More particularly, the lower jaw 26 of prior art vises typically includes an abutment 29 which engages the tip stop T of the key blank 30 (located at the nose of the blade portion of the blank) to locate and secure the position of the blank 30 along a first direction X. See FIG. 2B. The lower jaw may also engage the shoulder S of the key blank (located at the juncture of the bow and blade portions of the blank) to securely locate the blank along the direction X. As described further below, the lower vise jaw 26 includes a corner formed by surfaces 27, 28 for supporting the lower portion of the key blank blade. The heel H of blank 30 (located at the longitudinal edge of the lower portion 36 of the blade) abuts vertical surface 28 of lower jaw 26 so as to secure the position of blank 30 along a second direction Y. See FIG. 3. In this manner, and due to upper jaw 22 being moved into engagement with the blank 30, the position of the blank is fixed with the lower jaw 26 abutting the tip stop T and heel H of the lower portion 36 of the blade of key blank 30. Securing the key blank as shown in FIG. 3 positions the upper portion 34 of same horizontally where it is engaged by the punch (not shown) in a substantially horizontal direction.
The use of specially-configured key slots with corresponding key profiles to provide restricted key systems is known in the art. U.S. Pat. No. 5,176,015 to Sussina discloses a restricted key system comprising a chevron-shaped key slot (keyway) and corresponding key blank. The blade of the key blank includes an upper planar portion and a lower planar portion joined at an intermediate portion which forms a horizontal ledge. The lower planar portion extends away from the intermediate portion at a predetermined angle with respect to a vertical axis extending downward through the upper portion, which angle may be in the range of approximately 5-85.degree..
The Sussina patent teaches that the angled or chevron-shaped keys of the restricted key system will enter no other key slot or keyway but their own, i.e., the 5.degree. keys fit only the 5.degree. key slots, the 10.degree. keys the 10.degree. slots, etc., and that the proprietary chevron-shaped key slots will block entry of all prior art keys. The patent also teaches that a family of key sections (for example all keys with a 10.degree. angle) cannot be bitted (i.e., cut) by machines currently used by locksmiths or commercial key copiers.
Sussina teaches that the angled keys do not fit in and thus cannot be duplicated on conventional key cutting machines. Specifically, the lower angled leg of the key blank cannot be independently supported on key machine vises in current use, and even if the blank is supported on the vise, the cutter would produce bittings which are high on one side and would have to be finished by hand. As such, prior art apparatus are not able to suitably cut such angled keys.
Accordingly, there is a need in the art for an apparatus for supporting an angled or chevron-shaped key or key blank to facilitate proper cutting of bits in the blade thereof which avoids the problems present with prior art apparatus and produces consistent and accurate bit surfaces.